The present invention relates to teat cup assemblies for vacuum operated milking machines, and more particularly to a cartridge assembly enabling quick and easy replacement of a liner used in a teat cup assembly.
Conventional automatic milking machines utilize teat cup assemblies for milking cows. A typical teat cup assembly includes a hollow, rigid outer shell or cup adapted to be attached to a pulsating vacuum line, and an elongated, flexible, resilient, tubular inflation or liner which fits inside the shell and is coupled with a constant vacuum source. Typically, the inflation or liner includes an upper mouth, a barrel defining a teat-receiving region, and a milk tube section which extends downwardly out of the shell or cup and is attached to a milk claw for collecting milk. The upper mouth as well as the milk tube section are both sealingly engaged with the upper and lower ends of the shell, respectively, to form an annular vacuum chamber surrounding the barrel between the shell and the inflation. As previously noted, since the shell is attached to a pulsating vacuum line, the pressure in this annular chamber is alternated between subatmospheric pressure and atmospheric pressure. The constant vacuum applied to the lower milking tube section of the inflation draws milk from the cow's teat while at the same time the alternating pressure in the annular chamber periodically causes inward collapse of the barrel wall of the inflation or liner resulting in a massaging action on the teat. Also, the periodic collapse of the barrel intermittently relieves the teat from exposure to the constant vacuum applied to the interior of the inflation, and thus advantageously avoids complications such as inflammation of the teat as well as a tendency to induce mastitis.
Inflations or liners are typically composed of an elastomeric material due to the resilient nature of such material, i.e. its capability of recovering to its original size and shape after repeated deformation. Inflations or liners are most often made from a natural or synthetic rubber composition, e.g. silicone rubbers have been proposed and used in certain circumstances. Each of these materials have their own unique advantages and disadvantages. For example, natural or synthetic rubber compositions are more resistant to tearing or ripping, but are subject to attack by oils, butterfats, teat treatment preparations and other chemicals used in the milking process. On the other hand, silicone rubbers are substantially less vulnerable to attack by such chemicals, and thus, have relatively long useful life. However, silicone rubber tends to tear and puncture more easily than rubber.
If an inflation is ripped or torn, it must be replaced. Also, even if not ripped or torn, the inflation will eventually need to be replaced as it will deteriorate over time through continued use. In addition, under some circumstances, it would be an advantage to have the ability to replace an inflation made of a rubber composition with one made of silicone, or vice versa. Thus, it would be an advantage in the art to provide a teat cup assembly which enables the quick and easy replacement of the inflation.